How would we talk if anti-realism were true and we knew it to be true? We would talk as if it were true, presumably. For example, we would utter hypothetical statements about sense-experience, not categorical statements about material objects, assuming we knew phenomenalism to be true. We would speak of dispositions to behavior, not internal mental states, if we accepted behaviorism. We would refrain from reference to elementary particles, if we thought that there were no such particles to refer to. We would speak only of words and other symbols if we thought, as convinced nominalists, that no abstract entities exist (numbers, universals). We would restrict ourselves to overt expressions of emotion if we rejected the idea of moral values as objective entities, saying, “I approve of generosity” not “Generosity is good”. That is, if we were real anti-realists, as a matter of unreflective common sense, and had been forever, we would talk in the indicated manner. We would not talk misleadingly, as if realism were true, but accurately, reflecting our anti-realist convictions. We would talk in the way we now talk about things that we are anti-realist about—witches, ghosts, the ether, and the gods.
But that is not the way we actually talk. We talk as if realism were true: as if material objects were independent of experiences, as if mental states lie behind and cause behavior, as if elementary particles were tiny invisible bits of matter, as if numbers were different from numerals, as if moral values exist independently of human emotions. That is why anti-realism is always understood as a revisionary doctrine, not a purely descriptive one. We are natural realists—naïve realists, in the usual phrase. The anti-realist suggests that our normal and spontaneous realism is mistaken—so that we must change our views, and even our language. The anti-realist therefore sees himself as a critic of our ordinary ways of thinking, as they are expressed in our ordinary language. Thus we would (and should) speak and think differently, once we embrace the anti-realist’s position.
This means that anti-realism is always an error theory: there is some sort of mistake or distortion or sloppiness embedded in our usual discourse. The anti-realist about witches finds error in the discourse of those who speak uncritically of witches, and the anti-realist about material objects finds error in the notion that objects are distinct from sense experiences. Hence anti-realism is felt as surprising and disturbing. It would not be felt in that way if we were habitual anti-realists from birth till death. There would be no need to urge anti-realism on us if we already accepted it: in that situation it is realism that would be perceived as revisionary.
But if anti-realism is always an error theory, then it must account for the error. Why we do we make mistakes about ontological matters? Human error can arise in a number of different ways: perceptual illusion, indoctrination, prejudice, carelessness, random interference, etc. Thus we can explain errors in astronomy by perceptual illusions, errors in politics by prejudice, errors in morality by indoctrination. There are no inexplicable errors—errors that come from nowhere, for no reason, even if it is just random neural firings that are responsible. Much human error is temporary and quickly corrected, as with simple errors of fact, e.g. errors about the time of day, though some may take decades or centuries to be rectified. In all cases the error has some kind of intelligible explanation. But what is the anti-realist’s explanation of the errors that she detects? On the face of it, none—she has no explanation. She supposes that human beings have made enormous metaphysical errors, persisting over millennia, which have not been corrected in the usual ways: but nothing much is said about how such errors might have arisen. And the usual kinds of explanation for errors don’t seem to apply: no perceptual illusions or indoctrination or prejudice or hastiness. Many people have no doubt been browbeaten into accepting certain erroneous moral attitudes–at school, in church, and in the home–but surely no one has ever indoctrinated a child into being a moral realist or a perceptual realist or a Platonic realist (or if they have, it would be very rare). We don’t accept these realist positions because we have been coerced into them at an early age, still less because we are subject to perceptual illusions that suggest them; we just find ourselves holding realist opinions. We are not victims of relentless realist propaganda or a misfiring of the senses, being pushed towards a realist position we would naturally reject. So why do we commit the errors attributed to us by the anti-realist?
Some have suggested that ordinary language is to blame. Our perception of language is misleading as to its true nature—or some such. It is as if we gaze languidly at language and it actively produces metaphysical illusion in us—the illusion that realism is true. Thus it might be said that moral words look a lot like words for material objects, so we transfer realism from the latter to the former. But that would assume realism for material objects—so how do we explain the error that anti-realism detects in that area? Also, this kind of error theory is surely massively implausible: how could we be so easily bamboozled by the surface forms of our language? Why did no one point out the illusion centuries ago? Isn’t it just silly to suppose that the subject matter of a piece discourse should mirror the syntax of the discourse itself? Is it really remotely plausible to suppose that our habitual realism is the result of committing bizarre non-sequiturs from language to reality? And why is language so defective to begin with, given the truth of anti-realism? Would it be reasonable to claim that people believed in witches because of the way the word “witch” looks? Ordinary language, as we normally experience it, just doesn’t have the power to generate the kinds of metaphysical error that the anti-realist alleges.
So it appears that (a) anti-realism is an error theory and (b) it has no workable theory of error. Realism, by contrast, is not an error theory, and can simply claim that our commitment to it reflects the truth. If anti-realism has no explanation of the error it imputes, and if no such theory can be plausibly produced, then it must be itself erroneous. We thus have good reason to reject it. More strongly, anti-realism, in so far as it is an error theory, is a false theory—there is no such error in our ordinary thought and talk. Hence we should accept realism; and not just realism in this area or that, but realism across the board, since the problem with anti-realism is general and systematic.